Bay Area scientists dig into how to keep soils healthy as planet warms
With only 7.5% of Earth's surface covered in fertile, agricultural soil, it's critically important to maintain the soil to grow food, filter water, and regulate the climate. Today, Bay Area scientists are working to come up with a better understanding of how to keep our soil healthy in the age of climate change.
About 200 miles north of San Francisco in Butte County, cradled in the Sierra Nevada foothills, a team of scientists spent a weekend digging into the scorched earth. Dr. Jackie Pena, Lawrence Berkeley National Laboratory scientist and UC Davis civil and environmental engineer, along with her team carefully collected layers of dirt at the Big Chico Creek Ecological Reserve.
More than 98% of the reserve was damaged by the 2024 Park Fire, the fourth largest wildfire in California's history. The massive flames scorched more than 400,000 acres of land and soil.
"A lot of fires are happening following drought, and so the recovery is going to be happening under drier conditions," Peña said. "We're interested in understanding how the microorganism and plants are going to regenerate."
As the planet warms, the evidence shows how rising temperatures will do more than just increase the risk of extreme wildfires.
The changing climate may also fundamentally alter Earth's soil, and not just near the surface. Dr. Peña also has a research project unfolding in Marin County near Point Reyes National Seashore.
"We are collecting data over more than the top meter of the soil," Peña said.
The scientists are simulating climate change to study the effect of rising temperatures on the health of deeper soils. To start, they've installed aluminum pipes seven feet deep into the ground at about 20 different plots on the research location.
"It really does take a lot of careful planning to get all the sensors in the ground," explained Peña.
Some pipes contain heating devices to warm up the soil and whatever is in it by 4 or 6 degrees. Other pipes were used as controls and had no heating elements in them.
Soil contains an amazing hidden universe of minerals, decaying plants and animals, billions of bacteria and fungi, and tiny critters such as worms and spiders. In addition, it stores carbon.
"Soils on the earth represent a huge reservoir of carbon," said Berkeley Laboratory communications specialist Jeremy Snyder. "They hold three to four times more carbon than all of the atmosphere."
He explained how, with the rising temperatures, the microbes in the soil become more active and consume the buried carbon at a faster rate, which creates another problem.
"They are turning that carbon from a solid [in a] kind of stored-away, buried form back into carbon dioxide that goes into the atmosphere," said Snyder.
All that emitted carbon is a greenhouse gas that exacerbates the climate change issue.
In this project, different sensors and probes will measure the temperature of the soil, its moisture, and the carbon dioxide rising out of it. A solar panel will help to power the experiment, and wires from the plots are routed through a data system that measures the temperatures automatically.
"From each plot there is an individual wire, and they go into this data logger here to record the temperature every 15 minutes at our site," Peña said.
The team will also collect soil samples from the plots to analyze the results back at the lab.
"We know so little about what happens in the soil below the ground," Peña observed.
They hope to gather more data that will better inform and prepare a warming world for the future.